Gigabit Ethernet quenches Army's bandwidth thirst

By William Jackson

May 12, 1997

The Army site's "need for a backbone that won't affect other traffic is growing," said Steve Lewis, a former network design engineer with Dyncorp of Reston, Va., which runs the Aberdeen network. "Gigabit, from what we've seen so far, is going to work well."

At the headquarters building, Dyncorp has installed two Gigabit Ethernet switches with eight ports each from NBase Communications of Chatsworth, Calif., on the base's Fiber Distributed Data Interface network, Lewis said. Now that the headquarters staff has adapted, Aberdeen is ready to add more hubs, he said.

The move to Gigabit Ethernet is a tenfold leap from the 100-megabit/sec speed achieved over the network's current switched FDDI architecture.

Both asynchronous transfer mode and Integrated Services Digital Network have their places, said Aberdeen's chief information officer, John B. Ruhl. "But why not migrate once," he said. "100 megabits is a nice bandwidth, but with what we wanted to do, it wasn't going to be enough."

What the scientists at Aberdeen wanted to do was use more real-time video for data acquisition and move larger amounts of data quickly over the network to more users.

The proving ground is one of a handful of Defense Department test centers and is a repository for test data on all military equipment.

"Test cycles are drawing closer," Lewis said.

And as tests become more complex, evaluators want more data in real time.

In addition to data gathering, evaluators wanted to do more videoconferencing. All of this was a challenge for the 10-year-old fiber-optic network with 3,000 devices serving 1,000 users and more than a dozen test ranges.

"That can be done right now with existing technology, but if you get a lot of people using that, it's going to slow the network down," Ruhl said.

Ruhl and Lewis saw the future of networking in Gigabit Ethernet and took a calculated risk, agreeing to take the first of the fast switches that NBase produced.

"We made arrangements to be the first ones," Lewis said. "We also made the first offer to 3Com Corp. and Cabletron Systems Inc." But NBase was the first company to come through with the hardware.

The Institute of Electrical and Electronics Engineers does not expect to vote on standards for the technology, which transmits at 1 gigabit/sec over fiber-optic cable, until July. But the folks at Aberdeen were impatient. This was right in character for the Army facility that ordered the construction of the world's first electronic computer more than 50 years ago.

The Army wasn't going to wait for a product; it was going to emerge with it, Lewis said. "If it burps, we'll burp with it."

The risks were mitigated by the fact that both NBase and Cabletron agreed to upgrade their switches free of charge if needed to meet IEEE 802.3z standards when they are published. Besides, the industry has recognized the need for a common solution to gigabit transmission, Ruhl said.

"I think it's very low risk," he said. "It's not like we have a VHS machine and we're trying to put a Beta cartridge into it. We've moved video over it, audio over it, and everything has worked."

The proving ground has used videoconferencing equipment from PictureTel Corp. of Danvers, Mass., to test the high-speed links because there is no test equipment for Gigabit Ethernet yet, Lewis said.

Video and audio signals give evaluators an easy way to see and hear how the network is performing.

Gigabit switches eventually will replace all of the MMac-Plus LAN switches from Cabletron now being used at Aberdeen.

"I don't have the money to go right out and upgrade everything," Ruhl said. "Our plan is over the next year or two to upgrade the real high-volume users."

It will likely be four years before the entire network upgrade is complete, he said.